Harmonic balancer for vehicle road wheels



- March 7, 1939. I QLLEY 2,149,863

HARMONIC BALANCER FOR VEHICLE ROAD WHEELS Filed July 6, 1937 VUQLCANIZEI Wag/fits (OZ/5y by M%@ U NITED STATES HARDIONIC' BALANCER FOR VEHICLE ROAD WHEELS TE T OF FIE Maurice ()lley, Detroit, Mich., assignor to General Motors Corporation, Detroit, Mich a corporation of Delaware Application July 6, 1937, Serial No. 152,107

B-Claims. (Cl. 280-87-) This invention relates to motor vehicles and on the frame which occurs when the shock abparticularly to a harmonic balancer for damping sorber is checking wheel hop. the vertical oscillations of the road-wheels rela- The object of the invention is a harmonic baltively to the road. ancer of new and improved construction which In the conventional motorvehic'le, the'vehicle can be mounted in any suitable position on each 5 frame and the body are resiliently supported on ofthe independently movable unsprung masses the road wheel axles through suitable springs, of a vehicle to set up a force in a direction opposand the whole vehicle including the frame, the ing the force tending to cause wheel hop or verbody, the axles and the road wheelsyisresiliently tical oscillations of the unsprung mass relasupported on the road through the pneumatic tively to the road. in tires. Those parts 'of the vehicle which are'sup- A further object of the invention is a harmonic ported on the springs constitute the so-called balancer having pneumatic damping means. sprung mass and'thew'heels and their axles A still further object of the invention is to the so-called unsprung masses. apply the harmonic balancer to an independently to As the vehicle passes over road irregularities, suspended dirigible wheel in such a way that it there are oscillations of the whole vehicle relawill serve also to balance otherwise unbalanced tively to the road at a frequency dependent on forces tending to turn the wheel about its kingpin the combined rate of the springs and the tires, axis.

and of the wheels relatively to the road at a The above and other objects of the invention 9 frequency dependent chiefly-on the rate of the will be apparent as the description proceeds. 90 tires. The drawing shows the application of the in- The foregoing oscillations may take place to vention to an independently sprung dirigiblesome extent independently, and in every ccnwheel of that type in which a wheel supporting c'eivable combination, depending on the 'circumlever arm arranged longitudinally of the vehicle stances, (i. e., the loading, the character of the is mounted on a substantially horizontal pivot roadway, the speed of the vehicle, etc.). axis carried in a bracket which swings in a sub In the modern motor vehicle, low rate springs stantially hOr plane a o t a u st t al y having considerable deflection are employed to vertical kingpin mounted directly on the vehicle reduce the frequency of the oscillations of the framevehicle frame to a low and comfortable frequency. In the drawing: 30 The wheels and parts constituting the unsprung l is a P V Of One the diligiblfl from mass are, however, resiliently supported on the road wheels of a motor vehicle including part of road through the pneumatictires which have a the vehicle frame.

spring rate which is considerably higher than Fig. 2 is a front elevational view of Fig. 1.

5 the rate of the suspension springs, dependent on Fig. 3 is an enlarged sectional view on line 3-3 so the pressure and volume of the air they contain, of Fig. 2. and their deflection. The relative oscillations The Vehicle frame includes a transverse memof the sprung and the unsprung masses of her i rigidly attached thereto. Mounted at the the vehicle, are usually damped on bump or r end of the transverse member I, for pivotal movebound or both by suitable shock absorbers, but merit in asubstantially horizontal plane about a 40 when the shock absorbers are such as to most p o axis constituted by a king is a effectively damp these low frequency oscillations a ket of considerable amplitude, they are frequently The bracket 4 eXteIldS from the p n to less able to damp the higher frequency oscillawards the rear of the vehicle, and at its rearward 5 tions of th unsprung mas r lati l t th end provides support for the substantially hori- 4 road. 'Ihese higher frequency oscillations may zo t lp v x 0f the h l pp r n l ver be such that there is actual bouncing of the tires arm 6, carrying a Spi for the road Wheel on the road, which has been aptly described as with apneumatic tire 9. wheel hop. The effect is objectionable and to The bracket 4 is conveniently arra ged to conthe extent that the tires leave the road, traction stitute a housing for suitable spring means (not 50 and control of the vehicle is lost. It is very deshown), resiliently resisting pivotal movement of sirable that wheel hop should be damped by the wheel supporting lever arm relative to the means entirely unconnected with the vehicle bracket 4. frame, since by this means it is possible to avoid A drag link ill from a conventional steering the high frequency reaction of the shock absorber gear (not shown), is connected to a steering arm 55 As illustrated, this consists of a weight 13' resiliently held between a pair of air cushion springs M and of rubber or other suitable resilient material, and.- capable of oscillating upwards and downwards against the resistance of the air cushion springs.

The weight I3 is vulcanized as indicated, to

the air cushion springs l4 and I5, and the assembly consisting of the parts l3, l4 and I5 is held between brackets l1 and I8 which are rigidly attached to the brake backing plate l9 which is rigidly connected to the lever arm 5 and the spindle l of the wheel 8. The air cushion springs It and E5 are attached to the brackets IT and it! by bolts and 2|, provided with cap nuts 22 and 23, respectively. As shown the bolts 26 and 21 have thin fiat heads 24 and 25, which are sprung into pockets in the walls of the rubber cushions, to which they may be vulcanized.

If desired, the oscillations of the weight I3 may be clamped by providing for the influx and efliux of air at a restricted rate from the air cushion M. For this purpose the bolt 29 may be bored, counter-bored and screw threaded for a plug 2?, having a calibrated orifice 28 permitting air to flow at a selected rate between the air cushion and the atmosphere, through holes 29 and 30, in the walls of the air cushion l4 and the capnut 22, respectively.

The air cushion l5 may be provided with a tire valve 3! of conventional form, through which it may be inflated with air to the pressure required.

The harmonic balancer can be tuned to the frequency of the oscillations of the unsprung mass by varying the pressure in the air cushion 115 or by changing the degree of separation of the secured ends of the air cushions is and L5, as for example, by changing the distance apart of the brackets 11 and 18. Because of its inertia the weight l3 will through the air cushion springs Hi and I5 exert forces on the unsprung mass opposite in direction to the forces causing the oscillations of the unsprung mass, and by suitable proportioning of the parts of the harmonic balancer, the forces tending to cause wheel hop can be neutralized as they arise. It will be appreciated that the air cushions can be lighter in weight than equivalent metal springs so that they will but little increase the unsprung mass.

There is the further advantage that damping may be provided by causing the moving balance weight to pump air through orifices. This damping can be easily adjusted to requirements by adjusting the size of the orifice used.

While the invention is equally applicable to any type of vehicle wheel suspension, the drawing shows a particular arrangement as applied to a suspension system for a dirigible road wheel in which the masses which turn about the substantially vertical axis of the kingpin upon dirigible movement of the road wheel, are not equally disposed forwardly and rearwardly of the kingpin axis.

In such circumstances, when the vehicle is rounding a turn, there is a centrifugal moment tending to turn the wheel about the axis of the kingpin.

As illustrated, the essential parts of the suspension system result in a preponderance of mass to the rear of the kingpin axis. 7

According to the invention, the harmonic balancer is, with advantage, mounted in a position forwardly of the kingpin axis, such that in addition to its function as. a harmonic balancer for vertical oscillations, it has a centrifugal moment opposing the centrifugal moment otherwise tending to turn the wheel about its kingpin axis.

I claim:

1. In a vehicle having a sprung mass resiliently supported on the spindle of a road wheel, said road wheel and associated parts constituting unsprung mass of the vehicle, harmonic balancing means operative to counteract forces tending to cause vertical oscillations of the unsprung mass relatively to the road, said means comprising a weight resiliently supported for vertical oscillation between a pair of vertically spaced air cushion springs carried by the unsprung mass, the lowermost of said air cushion springs being inflated with air to a desired pressure and the uppermost of said air cushion springs being provided with a restricted orifice to atmosphere for the influx and efflux of air at a selected rate, to damp the oscillations of the weight.

2. The combination according to claim 1, in

which the road wheel and associated parts constituting the unsprung mass of the vehicle, includes a brake backing plate, the harmonic balancer being mounted on the brake backing plate.

3. In a vehicle having a sprung mass resiliently supported on the spindle of a road wheel mounted for dirigible movement about a substantially vertical pivot axis, the masses of the road wheel and associated parts being so disposed that when the vehicle is rounding a turnthere is a centrifugal moment tending to turn the road wheel about the said axis, means to counteract forces tending to cause vertical oscillations relatively to the road, of the road wheel and associated parts constituting unsprung mass of the vehicle, said means comprising a weight resiliently supported for vertical oscillation between a pair of springs carried on brackets on the unsprung mass said weight, springs, and brackets therefor, having such a mass and being so positioned relatively to the substantially vertical pivot'axis, that when the vehicle is rounding a 'turn, they will have a centrifugal moment opposing and neutralizing the centrifugal moment otherwise tending to turn the wheel about its said axis.

1 MAURICE OLLEY. 

